Generally, as shown in FIG. 1, an evaporator having a plurality of tube rows includes header units 101 and 102 provided in upper and lower sides, respectively, tubes 200 provided in two rows, one row in a front side and another row in a rear side, with respect to a flow of air, and a wrinkle fin 400 provided between the tubes. In the above structure, a heat exchange is implemented between a fluid flowing therein and air flowing between the tubes.
In the improvement of the thusly constituted evaporator, it is a primary object to decrease the whole dimension and enhance a heat exchange efficiency.
The conventional two-row tube evaporator which is improved based on the above object has the following disadvantages or problems.
First, the header unit adapted to connect two-row tubes is formed of a tank member and a header plate which are fabricated by a die casting or pressing fabrication method. Therefore, the assembling productivity is decreased compared to the materials extruded, and the fabrication cost is increased.
A path space of a fluid is partitioned by inserting a baffle into the interior of the header unit. In this case, since other baffle is assembled in the front and rear spaces portioned along the two-row tubes, the assembling productivity is decreased.
In addition, when assembling the tank member and header plate of the header unit, both sides of the header plate are laterally bent in the direction of the tank member and are temporarily welded (preferably, TIG welding) and then blazing-welded. In this case, the work process is increased. A defect rate is increased due to the transformation by the temporary welding operation.
Furthermore, since the front and rear two-row tubes are separately provided, when the air which have flown between the first-row tube flows between the second-row tube, since the air is crossed, thus decreasing a ventilation.
In addition, the conventional tubes are designed to have rounded lateral sides based on its inherent fabrication property during an extrusion formation. In the above construction, a condensation water produced during a heat exchange is not easily separated, namely flows in a lateral side, thus decreasing a heat exchange efficiency.
In the conventional header unit, since the portion into which a tube is inserted is formed flat, the condensation water from the tubes do not easily flow, namely gathers by a surface tension and capillary phenomenon.